I gave up all caffeine for no particular reason other than to 'give it a go' in August and now just drink fruit tea (twinings).
Had the usual headache after a few days but paracetomol got me thru those and i havent looked back.
It had the added unforeseen benefit of me losing more than ten pounds in weight too. I was 13 st 12 lbs but now hover around 13st to 13st 3lb. No, I didn't change anything else in my diet
I did seem to suffer a loss of power on my bike but don't know if this was just a mental thing. After putting in more miles over the next few months I felt okay again.